Women account for more than 11 million of incontinence cases. Moreover, a majority of women with incontinence suffer from stress urinary incontinence (SUI). Women with SUI involuntarily lose urine during normal daily activities and movements, such as laughing, coughing, sneezing and regular exercise.
SUI may be caused by a functional defect of the tissue or ligaments connecting the vaginal wall with the pelvic muscles and pubic bone. Common causes include repetitive straining of the pelvic muscles, childbirth, loss of pelvic muscle tone and estrogen loss. Such a defect results in an improperly functioning urethra. Unlike other types of incontinence, SUI is not a problem of the bladder.
Normally, the urethra, when properly supported by strong pelvic floor muscles and healthy connective tissue, maintains a tight seal to prevent involuntary loss of urine. When a woman suffers from the most common form of SUI, however, weakened muscle and pelvic tissues are unable to adequately support the urethra in its correct position. As a result, during normal movements when pressure is exerted on the bladder from the diaphragm, the urethra cannot retain its seal, permitting urine to escape. Because SUI is both embarrassing and unpredictable, many women with SUI avoid an active lifestyle, shying away from social situations.
In an effort to help manage female SUI, a physician may surgically place a supportive implant to raise the bladder neck and restore continence. These surgical devices, which are commonly referred to as “slings”, are placed in-vivo in a number of ways.
U.S. Pat. No. 5,112,344 describes a method and apparatus treating for female incontinence. The surgical instrument for the application of a filamentary element into the body comprises a tubular shaft having a handle at one end and a flexible needle slidably receivable in the shaft and adapted at one end to receive a filamentary element. The method of treating female incontinence comprises the steps of (1) looping the filamentary element between the wall of the vagina and the rectus abdominis sheath in the anterior wall of the abdomen, whereby the filamentary element passes to each side of the urethra; (2) adjusting the loop to bring the vaginal wall and the urethra into the correct spatial relationship to the pubis, thereby allowing the development of scar tissue between the vaginal wall and the anterior wall of the abdomen pubic symphysis; and (3) removing the filamentary element.
U.S. Pat. No. 5,899,909 discloses a surgical instrument comprising a shank having a handle at one end and connecting means at the other end to receive a pair of curved needles. In practice, a first needle is connected to one end of a tape, while a second needle is connected to an opposite end of the tape. The first needle is then passed into the body via the vagina, through the vaginal wall, and past one side of the urethra. The first needle is then further passed over the pubis and through the abdominal wall, thereby drawing the end of the tape through the body along one side of the urethra. The second needle is also passed into the body via the vagina, through the vaginal wall, and past an opposite side of the urethra. The second needle is then further passed over the pubis and through the abdominal wall, thereby drawing the opposite end of the tape through the body along an opposite side of the urethra, such that the tape forms a loop about the urethra. After the tape is extended over the pubis and through the abdominal wall, it is tightened. The tape ends are then cut at the abdominal wall, leaving the tape implanted in the body.
After placing the sling in the patient, the physician positions the sling with respect to the bladder and urethra. The position required to restore continence is individually determined for each patient by the surgeon. One method to position the sling is to provide the bladder with a predetermined stress or pressure and then the sling is positioned until continence is restored. The stress or pressure applied to the bladder may be provided in two different ways.
If the patient is awake, the physician may instruct the patent to apply abdominal pressure via muscle contraction, such as by coughing. This naturally applied force is considered to be the best gauge for “natural” continence evaluation. However, having the patient awake for this portion of the procedure is clinically inconvenient.
The second method is the most widely used procedure both domestically and internationally. Since the patient is typically anesthetized, requesting the patient to cough or pressurize the bladder is not possible. Consequently, the physician may apply firm positive pressure to the anterior pelvic portion of the body in an effort to induce micturition (i.e., the act of urinating). Pressure is applied repeatedly while the tape or sling is adjusted. The tape is adjusted until only a minor trace of the fluid flow exits the urethra.
When a patient is under general anesthesia and in the supine position, abdominal and skeletal retention muscles are inactive. When manual pressure is applied as in the aforementioned manner, it is believed that the force/pressure focused on the bladder is actually dissipated by the overall relaxed state of the lower abdomen. Gauging tape position and subsequent urodynamics in this manner is extremely dangerous and can lead to adverse conditions, such as urethral restriction, or may maintain incontinence.
The physician may choose to directly pressurize the bladder during either of the two procedures described above to more closely simulate the effect of exerting stress on a full or partially filled bladder. Such direct pressurization is achieved by inserting a catheter through the urethral sphincter, by way of the urethral canal, into the bladder, then passing a known volume of fluid into the bladder, then withdrawing the catheter past the urethral sphincter. The remainder of the procedure is carried out as described above. This procedure is necessarily invasive and discomforting to the patient.
Thus, there is a need for an apparatus and method for measuring and monitoring urodynamic flow and pressure variations while positioning the tape in such a way to provide the physician with the exact information needed to ensure optimal clinical safety and efficacy of the tape, as demonstrated by the urinary apparatus of the present invention.
The present invention overcomes the deficiencies of the prior art and provides for an improved urodynamic measurement system that may be used in conjunction with any procedure to treat SUI such as those to suspend the bladder neck or support the urethral sphincter muscle. The measurement system does not require pressurization of the bladder and, therefore, is less invasive than methods which involve direct injection of fluids through the urethral sphincter into the bladder. For illustrative purposes only, the present invention will be discussed in combination with the apparatus and method disclosed in the aforementioned U.S. Pat. No. 5,899,909.